linux/mm/page_idle.c
Minchan Kim e4b8222271 mm: make rmap_one boolean function
rmap_one's return value controls whether rmap_work should contine to
scan other ptes or not so it's target for changing to boolean.  Return
true if the scan should be continued.  Otherwise, return false to stop
the scanning.

This patch makes rmap_one's return value to boolean.

Link: http://lkml.kernel.org/r/1489555493-14659-10-git-send-email-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-05-03 15:52:10 -07:00

234 lines
5.4 KiB
C

#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/fs.h>
#include <linux/sysfs.h>
#include <linux/kobject.h>
#include <linux/mm.h>
#include <linux/mmzone.h>
#include <linux/pagemap.h>
#include <linux/rmap.h>
#include <linux/mmu_notifier.h>
#include <linux/page_ext.h>
#include <linux/page_idle.h>
#define BITMAP_CHUNK_SIZE sizeof(u64)
#define BITMAP_CHUNK_BITS (BITMAP_CHUNK_SIZE * BITS_PER_BYTE)
/*
* Idle page tracking only considers user memory pages, for other types of
* pages the idle flag is always unset and an attempt to set it is silently
* ignored.
*
* We treat a page as a user memory page if it is on an LRU list, because it is
* always safe to pass such a page to rmap_walk(), which is essential for idle
* page tracking. With such an indicator of user pages we can skip isolated
* pages, but since there are not usually many of them, it will hardly affect
* the overall result.
*
* This function tries to get a user memory page by pfn as described above.
*/
static struct page *page_idle_get_page(unsigned long pfn)
{
struct page *page;
struct zone *zone;
if (!pfn_valid(pfn))
return NULL;
page = pfn_to_page(pfn);
if (!page || !PageLRU(page) ||
!get_page_unless_zero(page))
return NULL;
zone = page_zone(page);
spin_lock_irq(zone_lru_lock(zone));
if (unlikely(!PageLRU(page))) {
put_page(page);
page = NULL;
}
spin_unlock_irq(zone_lru_lock(zone));
return page;
}
static bool page_idle_clear_pte_refs_one(struct page *page,
struct vm_area_struct *vma,
unsigned long addr, void *arg)
{
struct page_vma_mapped_walk pvmw = {
.page = page,
.vma = vma,
.address = addr,
};
bool referenced = false;
while (page_vma_mapped_walk(&pvmw)) {
addr = pvmw.address;
if (pvmw.pte) {
referenced = ptep_clear_young_notify(vma, addr,
pvmw.pte);
} else if (IS_ENABLED(CONFIG_TRANSPARENT_HUGEPAGE)) {
referenced = pmdp_clear_young_notify(vma, addr,
pvmw.pmd);
} else {
/* unexpected pmd-mapped page? */
WARN_ON_ONCE(1);
}
}
if (referenced) {
clear_page_idle(page);
/*
* We cleared the referenced bit in a mapping to this page. To
* avoid interference with page reclaim, mark it young so that
* page_referenced() will return > 0.
*/
set_page_young(page);
}
return true;
}
static void page_idle_clear_pte_refs(struct page *page)
{
/*
* Since rwc.arg is unused, rwc is effectively immutable, so we
* can make it static const to save some cycles and stack.
*/
static const struct rmap_walk_control rwc = {
.rmap_one = page_idle_clear_pte_refs_one,
.anon_lock = page_lock_anon_vma_read,
};
bool need_lock;
if (!page_mapped(page) ||
!page_rmapping(page))
return;
need_lock = !PageAnon(page) || PageKsm(page);
if (need_lock && !trylock_page(page))
return;
rmap_walk(page, (struct rmap_walk_control *)&rwc);
if (need_lock)
unlock_page(page);
}
static ssize_t page_idle_bitmap_read(struct file *file, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t pos, size_t count)
{
u64 *out = (u64 *)buf;
struct page *page;
unsigned long pfn, end_pfn;
int bit;
if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
return -EINVAL;
pfn = pos * BITS_PER_BYTE;
if (pfn >= max_pfn)
return 0;
end_pfn = pfn + count * BITS_PER_BYTE;
if (end_pfn > max_pfn)
end_pfn = ALIGN(max_pfn, BITMAP_CHUNK_BITS);
for (; pfn < end_pfn; pfn++) {
bit = pfn % BITMAP_CHUNK_BITS;
if (!bit)
*out = 0ULL;
page = page_idle_get_page(pfn);
if (page) {
if (page_is_idle(page)) {
/*
* The page might have been referenced via a
* pte, in which case it is not idle. Clear
* refs and recheck.
*/
page_idle_clear_pte_refs(page);
if (page_is_idle(page))
*out |= 1ULL << bit;
}
put_page(page);
}
if (bit == BITMAP_CHUNK_BITS - 1)
out++;
cond_resched();
}
return (char *)out - buf;
}
static ssize_t page_idle_bitmap_write(struct file *file, struct kobject *kobj,
struct bin_attribute *attr, char *buf,
loff_t pos, size_t count)
{
const u64 *in = (u64 *)buf;
struct page *page;
unsigned long pfn, end_pfn;
int bit;
if (pos % BITMAP_CHUNK_SIZE || count % BITMAP_CHUNK_SIZE)
return -EINVAL;
pfn = pos * BITS_PER_BYTE;
if (pfn >= max_pfn)
return -ENXIO;
end_pfn = pfn + count * BITS_PER_BYTE;
if (end_pfn > max_pfn)
end_pfn = ALIGN(max_pfn, BITMAP_CHUNK_BITS);
for (; pfn < end_pfn; pfn++) {
bit = pfn % BITMAP_CHUNK_BITS;
if ((*in >> bit) & 1) {
page = page_idle_get_page(pfn);
if (page) {
page_idle_clear_pte_refs(page);
set_page_idle(page);
put_page(page);
}
}
if (bit == BITMAP_CHUNK_BITS - 1)
in++;
cond_resched();
}
return (char *)in - buf;
}
static struct bin_attribute page_idle_bitmap_attr =
__BIN_ATTR(bitmap, S_IRUSR | S_IWUSR,
page_idle_bitmap_read, page_idle_bitmap_write, 0);
static struct bin_attribute *page_idle_bin_attrs[] = {
&page_idle_bitmap_attr,
NULL,
};
static struct attribute_group page_idle_attr_group = {
.bin_attrs = page_idle_bin_attrs,
.name = "page_idle",
};
#ifndef CONFIG_64BIT
static bool need_page_idle(void)
{
return true;
}
struct page_ext_operations page_idle_ops = {
.need = need_page_idle,
};
#endif
static int __init page_idle_init(void)
{
int err;
err = sysfs_create_group(mm_kobj, &page_idle_attr_group);
if (err) {
pr_err("page_idle: register sysfs failed\n");
return err;
}
return 0;
}
subsys_initcall(page_idle_init);